Manufacture of insulated electric conductors



" www June 15.1954-, D. fr. HoLLmiGsWQRTl-lv ET A;MANUFACTUREbF'INSULATED ELEGTRCCONDUCTORS' Filed Oct. 29, 1951- MPatented June 1,1!954 f UNITED STATES PATENT OFFICE MANUFACTURE 0FINSULATED ELECTRIC CONDUCTORS Douglas Taft Hollingsworth,v Knutsford,and

James Alexander McCleery, Sale, England, assignors to W. T. Glover & Co.Limited, Manchester, England, a British company Application October 29,1951, Serial No. 253,686

Claims priority, application Great Britain November 14, 1950 3 Claims..(Cl. 154-225) l 2 This invention relates to insulated electric conformedaxially of a member 4. In its extreme ductors of the kind in which theconductor (01' forward position the front end of the ram I isconductors) is enclosed in a metal tube and insudisposed just inside thecorresponding end of the lated from it by powder, for instance, magnesiamember 4, as will be seen from the drawing. or talc. The inventionprovides an improved 'i The member 4, referred to hereinafter as themanufacture carried out by a process in which inner member, cooperateswith an outer member the powder is fed into a tube around the con- 5 toform a shaping die for a metal strip of approductor and compressedthere. priate width which is fed in a continuous manner In accordancewith the invention the insulated through the apparatus. The outer memberof conductor (or conductors) is manufactured by a l that die isrelatively short as compared with the Continuous process in which theenclosing tube inner member and between the two members is is formed bythe gradual transverse bending of a an appropriately shaped passage 6which extends Strip of metal Which iS Continuously moving forforwards ina direction towards the longitudinal. Ward, the bending bringing theedges together, axis of the apparatus and tapers in. width in thatyafter which they are united by welding or by l direction. I'he innermember 4 has a rear por-- soldering (soft or hard solder). In thiscontinution 'I having a wall thickness which is gradually ous processthe conductor (or conductors) also reduced in the forward direction, anintermediate travels forward with the strip and becomes enportion 3 ofuniform wall thickness and a front.

CIOSed in the tube. AS the bending 0f the Strip portion 9, whichgradually tapers in thickness; 'proceeds the odgeS of the Strip arebrought closer 20 and then continues as a cylindrical portion of.'

and closer together and at an appropriate place uniform Wall thickness,

in the path of the Strip the powder iS fed through The cylindricalintermediate part Il of the inner the gap between the edges of thecurved strip member 4 is surrounded by and spaced from an t0 a place infront of a reciprocating ram- From outer cylindrical casing ill, theupper part of.' that region the powder is pushed forward into which hasan aperture II through which insulat the closed part of the strip andconsolidated there ing powder for a conductor i2 can be fed inter-i bythe ram. The conductor (or conductors) mittently and in appropriatequantities through passes through a hole in the ram. After the a feedhopper I3. Immediately in front of the edges of the strip have beenunited to form a` casing I0 which cooperates with the intermeclosedtube, the latter ,proceeds forward to a diate cylindrical part 3 of theinner member 4 to reducing die through which it is drawn, underform anelongated cylindrical die, is a member going in the process a reductionof diameter and I4 which cooperates with the adjacent surface 'a furthercompression of the powder within it. of the front portion 9 of the innermember 4 to The invention will be described further with provide aforming die which serves to bring tothe aid of the accompanying drawingsillustrating gether in abutting relationship the two edges of one formof construction by way of example and a strip passing through themachine.

wherein The forward end of the passage B is in com- Figure 1 is alongitudinal view, partly in secmunication with the passage providedbetween tion, the figure being largely diagrammatic and the intermediateportion 8 and the casing ID and not drawn to scale, the latter, at itsfront end communicates with the Figure 2 is a longitudinal view, partlyin secpassage provided between the member I4 and tion, of a part of theapparatus shown in Figure 1 the front portion 9 of the inner member 4.and drawn to an enlarged scale, Immediately in front of the member !I4is a Figures 3, 4, 5 and 6 are sectional end elevadevice I5 whichsolders or otherwise joins totions taken on the lines III-III, IV-IV,V-V, 45 gether the abutting edges of the strip to form VI--VIrespectively of Figure 2. a complete tube, the diameter of which isreduced In the following description that end of the by drawing the tubethrough o die I6 by any apparatus shown to the left of the figure isresuitable means. garded as being the rear end and the opposite The ramI has an axially disposed passage I8 end, as the from; end, throughwhich the conductor I2, drawn oir from The apparatus comprisesareciprocating rami o bobbrl i9, paSSoS in a Continuous morir-or,

working in a cylinder 2. The ram at its forward entering the passage atthe rear end of the ram. part is of reduced diameter and extends forsome The conductor passes over a guide roller 20 and considerabledistance beyond the end of its cylthen passes in a straight line throughthe ram I.

inder where it passes into a cylindrical passage 3 55 The metal stripwhich is formed continuously..

into a tube and which encloses the conductor insulated with powder fedin through the hopper I3, is shown at 2l, 22 being a supply bobbin fromwhich the at strip is drawn off, through a tension control device 23 andaround a guide roller 24. From the latter, the strip 2l passes through apreforming device 25 (see particularly Figure 3) into the front end ofthe passage 5. The de vice 25 has a transversely extending slot 84through which the strip 2l passes, the slot commencing the shaping ofthe strip by bending it transversely to its length to facilitate itsentry into the passage 6 where the main part of the transverse bendingof the strip is effected and the edges of the strip caused to movetowards each other and to provide between those edges a gap whichgradually decreases in width in a direction towards the front end of theapparatus. After passing through the device 25, the strip passes frombelow the rear end of the cylinder 2 into the rear end of the passage 6.

During the passage of the strip through the casing l0, a small quantityof powder is discharged from the feed hopper I3, to the front orworkingl end of the ram l which is then positioned (see Figure 2) ashort distance to the rear of a port 28 in the intermediate part 8 ofthe inner member 4. The powder falls from the feed hopper through theaperture l l in the casing ID, through the gap between the edges of theshaped strip (see Figure and through the port 26 into the intermediatepart 81. As the ram advances on its working stroke it closes the port26, and pushes the powder in front of it, the ram continuing to move inthe same direction until it enters that part of the tube where the edgesof the tube have been joined together by the device I5 which completesthe formation of the tube by soldering or otherwise joining the edgestogether. 'Ihe ram moves with clearance in this part of the tube andpresses the powder around the axially disposed conductor and alsoconsolidates the latter. The completed tube 29 and enclosed insulatedconductor then pass together through the drawing down die i8 whichfurther compresses the powder insulation. An appropriate form of pullingdevice indicated by Il may be used for pulling the insulated conductorwith its enclosing tube through the die i5.

The reciprocation oi the ram l at an appropriate rate is eilected by adouble acting. device 2 comprising a piston working in a cylinder, airunder pressure being fed into the cylinder alternately to opposite sidesof the piston. The collar 28 on the ram serves as an emergency stop.

The broken line 3B indicates the path of an edge of the strip 2l as thelatter passes from the pre-shaping device 25 to the space between themember Hi and the front portion 9 of the inner member 4l.

The ram l reciprocates in bearings 3l and at its front end, the innermember 4 is formed with a recess 32 which receives packing material 33to avoid the risk or" powder reaching the bearings.

What we claim as our invention is:

1. A method of manufacturing a conductor insulated with powder andenclosed in a metal tube, by a continuous process, comprisinglcontinuously advancing in the direction of its length a metal strip,subjecting the said strip, as it advances, to a transverse bending toeect relative movement of approach of its longitudmai edges and to giveto the strip a tubular shape with a gap between its longitudinal edges,continuously advancing a conductor in the direction of its length intothe tubular shaped part of the strip, supplying insulating material inthe form of powder through the gap between the longitudinal edges of thetubular part of the strip to the interior of that part, joining togetherthe longitudinal edges of the tubular part at a place in advance of thatat which the supply of insulating powder takes place thereby forming acomplete tube, pushing forward the powder in the tubular part to a placeadjacent that at which the longitudinal edges have been joined togetherand reducing the diameter of the complete tube, thereby compressing thepowder therein.

2. An apparatus for the manufacture, as a continuous operation, of apowder-insulated conductor enclosed in a metal tube, comprising ashaping die which transversely bends a metal strip passing therethroughto form an incomplete tube having a gap between its longitudinal edges,a reciprocable ram working in a bore in the shaping die, a device forfeeding a powder insulant through the gap in the incomplete tube to theinterior of the latter in front of the reciprocable ram, means forclosing the gap in the incomplete tube to form a complete tube, the saidgap-closing means being mounted in advance of the powder-feeding device,a drawing-down die mounted in advance of the gap-closing means, andmeans for drawing the complete tube t0- gether with a wire and powderinsulant therein through the drawing-down die, reducing the diameter ofthe tube and compressing the powder therein.

3. An apparatus for the manufacture, as a continuous operation, of apowder-insulated conductor enclosed in a metal tube, comprising ashaping die comprising spaced inner and outer members having theiradjacent surfaces shaped to bend a metal strip passing therebetween intotubular form with a gap between its longitudinal edges, thereby formingan incomplete tube, the inner member of the shaping die having a boretherein, a reciprocable rain workingin the bore and having alongitudinally extending passage, a feed device for discharging powderthrough the gap in the incomplete tube in front of the ram, means forclosing the said gap to form a complete tube, the ram having aworkingstroke which extends to a point adjacent the gap-closing means, adrawing-down die mounted in front of the latter and means for drawing ametal strip through the shaping die and a wire through the passage inthe ram and the completed tube together with the wire and powderinsulant within the tube, through the drawing-down die to reduce thediameter of the tube and compress the powder.

References Cited in the le of this patent UNITED STATES PATENTS NumberName Date 289,725 Tainter Dec. 4, 1883 1,233,807 Read July 17, 19172,088,446 Specht July 27, 1937 2,123,778 Heilmann July 12, 19382,389,705 Wetzel Nov. 27, 1945

1. A METHOD OF MANUFACTURING A CONDUCTOR INSULATED WITH POWDER ANDENCLOSED IN A METAL TUBE, BY A CONTINUOUS PROCESS, COMPRISINGCONTINUOUSLY ADVANCING IN THE DIRECTION OF ITS LENGTH A METAL STRIP,SUBJECTING THE SAID STRIP, AS IT ADVANCES, TO A TRANSVERSE BENDING TOEFFECT RELATIVE MOVEMENT OF APPROACH OF ITS LONGITUDINAL EDGES AND TOGIVE TO THE STRIP A TUBULAR SHAPE WITH A GAP BETWEEN ITS LONGITUDINALEDGES, CONTINUOUSLY ADVANCING A CONDUCTOR IN THE DIRECTION OF ITS LENGTHINTO THE TUBULAR SHAPED PART OF THE STRIP, SUPPLYING INSULATING MATERIALIN THE FORM OF POWDER THROUGH THE GAP BETWEEN THE LONGITUDINAL EDGES OFTHE TUBULAR PART OF THE STRIP TO THE INTERIOR OF THAT PART, JOININGTOGETHER THE LONGITUDINAL EDGES OF THE TUBULAR PART AT A PLACE INADVANCE OF THAT AT WHICH THE SUPPLY OF INSULATING POWDER TAKES PLACETHEREBY FORMING A COMPLETE TUBE, PUSHING FORWARD THE POWDER IN THETUBULAR PART TO A PLACE ADJACENT THAT AT WHICH THE LONGITUDINAL EDGESHAVE BEEN JOINED TOGETHER AND REDUCING THE DIAMETER OF THE COMPLETETUBE, THEREBY COMPRESSING THE POWDER THEREIN.
 2. AN APPARATUS FOR THEMANUFACTURE, AS A CONTINUOUS OPERATION, OF A POWDER-INSULATED CONDUCTORENCLOSED IN A METAL TUBE, COMPRISING A SHAPING DIE WHICH TRANSVERSELYBENDS A METAL STRIP PASSING THERETHROUGH TO FORM AN INCOMPLETE TUBEHAVING A GAP BETWEEN ITS LONGITUDINAL EDGES, A RECIPROCABLE RAM WORKINGIN A BORE IN THE SHAPING DIE, A DEVICE FOR FEEDING A POWDER INSULANTTHROUGH THE GAP IN THE INCOMPLETE TUBE TO THE INTERIOR OF THE LATTER INFRONT OF THE RECIPROCABLE RAM, MEANS FOR CLOSING THE GAP IN THEINCOMPLETE TUBE TO FORM A COMPLETE TUBE, THE SAID GAP-CLOSING MEANSBEING MOUNTED IN ADVANCE OF THE POWDER-FEEDING DEVICE, A DRAWING-DOWNDIE MOUNTED IN ADVANCE OF THE GAP-CLOSING MEANS, AND MEANS FOR DRAWINGTHE COMPLETE TUBE TOGETHER WITH A WIRE AND POWDER INSULANT THEREINTHROUGH THE DRAWING-DOWN DIE, REDUCING THE DIAMETER OF THE TUBE ANDCOMPRESSING THE POWDER THEREIN.